Dredging devices for removing material hydraulically from a submerged surface have long been known. These devices are generally suspended from a vessel and are supplied with water or other fluids under pressure to dig and otherwise remove material from the submerged surface in order to, for example, lay a buried pipe or to clear a channel in a harbor.
These early material removing devices have all been incapable of operating effectively unless a prescribed fluid delivery capability for the entire device was available. Thus, the unit could not function sufficiently at, for example, a flow rate of half what was required for the entire unit. Also, these devices could not localize the digging action on command in order to concentrate the digging action at a particular location.
It is therefore an object of this invention to provide apparatus for removing material from a submerged surface which is capable of directing the applied hydraulic fluid material to one or more zones of the device whereby the jetting action is localized and the device may function effectively even though the source of pressurized fluid is limited or impaired. Other objects of the invention include providing a stable and controllable apparatus capable of resting on the submerged surface and an apparatus in which both water and air urge the removed material into a material receiving housing to remove the material from the area from which it was removed.